Thermally responsive device



Feb. 28, 1956 J. c. ALBRIGHT 2,736,604

THERMAL-LY RESPONSIVE DEVICE Fued May 15, 1950 2 Sheets-Sheet 1Z'mventor Jay/v CI zQLBE/SH? Gttomegs 2 Sheets-Sheet 2 v Mai Gttorneg;

1956 J. c. ALBRlGHT THERMALLY RESPONSIVE DEVICE Filed May 15, 1950 mumUnited States Patent 2,736,604 THERMALLY RESPONSIVE DEVICE John C.Albright, Chicago, 111., assignor to William J. Adams, Chicago, 111.Application May 15, 1950, Serial No. 161,956 13 Claims. c1. 297-6 Thisinvention relates to a thermally responsive device. The presentapplication is a continuation in part of application 55,797, filedOctober 21, 1948, now Patent No. 2,593,238. Claims divided from the saidparent application have been transferred hereto.

As in. the said parent application, it is broadly the object of theinvention to provide improved means for concentrating the pressure of asubstantial body of thermally expansible material on a plunger ofrelatively small cross sectional area to produce relatively large axialresponse of the plunger. This application also has in common with itsparent application the objective of protecting the diaphragm againstdestruction which usually follows when a diaphragm is repeatedly subjectto bending stress.

In the present case as well as in the parent application aboveidentified, it is sought to prolong the life of the diaphragm by makingit in one piece with a deformable liner for at least a portion of thechamber which contains the thermally responsive material, the saidchamber having surfaces which taper curvilinearly and reversely from thelarge diameter of the chamber to the small diameter of the cylinder andthe liner being extended from the diaphragm in the cylinder smoothlyalong the curvilinear surfaces and to a remote anchorage in the chamber.

Objects specific to the present invention include the provision of askirted diaphragm which desirably extends upwardly into the cylinder andpreferably depends primarily upon attenuation rather than deformation toaccommodate expansive movement resulting from the expansion of thecrystalline material; the provision of a chamber construction in whichbridging of the crystalline expansion material in the course of thecooling thereof is prevented and cooling from the center of the massoutwardly is promoted; and the provision of a composition in which theexpansion material is distributed throughout a mass of inert materialwhich not only separates but lubricates the crystals as they form tominimize any bridging tendency.

In the drawings:

Fig. 1 is a view in side elevation on a greatly enlarged scale of adevice embodying the invention.

Fig. 2 is a view in vertical axial section through the device of Fig. 1.

Fig. 2a is a view in axial section through the combined diaphragm andskirt used in the devices of Fig. 1.

Fig. 3 is a view similar to Fig. 2 showing a slightly modifiedembodiment of the invention.

Fig. 4 is a view in axial section through another modified embodiment ofthe invention.

Fig. 5 is a fragmentary detail view partially in side elevation andpartially in axial section showing a modified diaphragm and skirtarrangement usable in any of the embodiments herein disclosed.

Fig. 6 is a view in vertical axial section through another modifiedembodiment of the invention.

Fig. 7 is a view taken in cross section on the line 7-7 of Fig. 6.

Fig. 8 is a fragmentary detail view in axial section showing a furthermodified embodiment of the invention.

Figs. 9, 10 and 11 are 'views similar to Fig. 8 showing further modifiedembodiments.

The devices disclosed are not equivalents except in a generic sense,since specifically each. has advantages and for most purposes theconstruction shown in Figs. 1 and 2 is preferred.

The container 15 is made in two parts 16 and 17 having complementaryradial flanges at 18 and 19, respectively, these being encircled by aring 20 of channel-shaped cross section which holds the flanges togetherunder pressure on the intervening flange 21. of a liner for a chamberportion 16 which includes, desirably in one piece, a diaphragm and plugelement 22 in the skirt 23 and an intervening portion 24 which isreversely curved in axial section to con nect the relatively largediameter of the skirt 23 with the relatively small diameter of thediaphragm or plug 22. This liner is complementary to the inner surfaceof the chamber element 16, to which it conforms exactly. At the upperend of the chamber portion is a cylinder 25 for plunger 26. Thediaphragm of plug portion 22 of the liner is disposed in, and fits thecross section of, the cylinder 25 and abuts the lower end of the plunger26. In use, the plunger will be subject to the bias of a compressionspring such as that shown at 27 in Fig. 6 to be confined between thespring seat cup 28 and a flange 29 on the plunger 260 which is thereillustrated. The showing of such a spring has been omitted from thedevice of Figs. 1 and 2 because the thermostatic unit may be soldWithout any such spring and derive a return bias for its plunger fromthe organization in which it is used.

The space within the container 15, and within the liner thereof iscompletely filled with a thermally expansible material 30. While it isbroadly immaterial What the composition of this substance is, variousexamples being given in the companion application above identified, itis referred to use, as the active ingredient, a material which iscrystalline at atmospheric temperature and which melts at approximatelythe temperature at which thermostatic response is desired, the meltingbeing accompanied by a substantial increase in volume. Such a materialmay conveniently comprise paradichlorobenzene. For reasons hereinafterexplained, it is desired first, to separate and, secondly, to lubricateor reduce friction between the crystals of the active thermostaticmaterial. For this reason, I prefer to use with the material some inertsubstance such as powdered chalk plasticized with some oil which in nomanner interacts with the paradichlorobenzene or other thermallyresponsive active ingredients. The amount and character of the inertpowder and the oil are not critical. I have used successfully theidentical composition of chalk and linseed oil which is used as putty inglazing windows and in which, at a temperature of F. I have stirredparadichlorobenzene until a thorough mixture was effected. In preparingthe putty, any other inert powder such as clay or rouge or silica flourmay be substituted for the chalk, and such oils as glycerin, any of thepolyglycols and any of the lighter silicones may be substituted for thelinseed oil.

In practice, I have found the most desirable proportions to be 40% ofcrystals of paradichlorobenzene or the like and 60% of putty by weight.As above indicated, any other inert material and plasticizer arecomprehended within the term putty. I may use as low as 40% of theselected crystals and 60% of the putty. There is no sharply definedlimit, but the length of travel is reduced as the percentage of crystalsin the composition is reduced. If I use greatly in excess of 60% of thecrystals, I do not obtain full relief from the bridging phenomenon ashereinafter described.

The composition is non-homogeneous, since the crys- 3 tals may bedisposed anywhere in the inert putty. They tend, however, to be quiteuniformly distributed throughout the composition when the proportionsare within the indicated range.

In the assembly of the parts, the composition is packed into the chamberand inside of the liner under sufficient pressure to eliminate voids.

A thermally conductive post which may be tubular as shown at 31 in Fig.2, or solid as shown at 310 in Fig. 3, is integral with the base memberof the chamber and projects centrally up into the chamber as shown. Thepurpose of this is to conduct to the outside of the chamber the heatfrom the body of composition at 30 which fills the chamber. I have foundthis to be very important in promoting the initial crystallization ofthe acting thermostatically responsive ingredient at points remote fromthe upper end of the chamber. I have found that the action in thisregard can be slightly enhanced if the surfaces of the post which areexposed to the composition are left somewhat rough instead of beingsmoothly finished.

Another desirable, though not strictly essential, feature consists inthe provision within the flange 19 of the lower chamber element 17 of achannel 33 lying between the outer head of the flange and an annular rib34 which encircles its inner head. In practice, there is providedbetween the rib 34 and the opposing flange 18 a clearance ofapproximately half the thickness of the flange 21 of the rubber liner.Assuming the flange to be .02 inch in thickness, the clearance would beapproximately .01 inch in thickness, this spacing being maintaineddespite actual metal engagement of the flanges at their outerperipheries to prevent the pressure used in closing the chamber fromcompletely severing the flange of the rubber liner. The initial form ofthe flange 21 of the rubber liner may be such that it also has amarginal rib at 210 (Fig. 2a) which, however, is merely to provideadditional stock without necessarily registering with channel 33.

It is not necessary that all of the semi-fluid material within thedevice comprise the active ingredient or the composition as abovedescribed. Fig. 4 shows an organization closely comparable to that ofFig. 2 with the exception that the chamber in Fig. 4 is subdivided by aflexible partition at 35, the margins of which are clamped, along withthe flange 21 of the liner 23, between the flange 18 of the upperportion of the shell and the flange 19 of the lower portion thereof. Thecentral conductor post 331 is made tubular, like that of Fig. 2, but hasa flat top against which the partition diaphragm 35 is normally seated.The entire lower portion 171 of the shell is filled with the thermallyresponsive crystalline composition 301 while the upper portion 16 of theshell, above the partition, is filled with an inert semi-fluid materialat 302, which may comprise putty or the like, and the function of whichis simply to transmit to the plunger 261 the pressure developed by thecrystalline powder, and, during contraction, to transmit to thecrystalline material the compression to which the plunger 261 may besubject in use. As before, the device is highly sensltlve because of thefact that the crystalline thermally responsive material lies in anannular zone having both nner and outer metallic walls through whichheat transfer is very rapid.

The operation of the device as thus far described Will be summarized inorder that the advantages of the constructlon disclosed may be morefully apparent.

The thermostatic capsule as shown in Fig. 1 may be assumed to be inoperation for thermostatically controll1ng a Water valve to effectmovement thereof at approxlmately 130 F. At this temperature, themelting of the crystals of the active thermostatic ingredient of thecomposition 30 will cause rapid expansion which will attenuate the linerin the upper part of container 15 throughout substantially its entireheight, from its P0int 4 of anchorage at flange 21 to its diaphragm orplug portion 22.

The movement of the plug or diaphragm 22 is communicated to the plunger26 to effect axial movement thereof. Because a relatively large body ofmaterial is expanding into the relatively small cross section of thepiston cylinder 25, the plunger will have relatively great movement. Yetit will be observed that the movement of the liner skirt and diaphragmdoes not involve any flexion across a shoulder or edge, but only flowalong curvilinear surfaces. The increase in length of the liningmaterial from the larger cross section of the chamber 16 into thecylinder 25 results in considerable attenuation, but the movement from alarge cross section into a smaller cross section involves lateralcompression, so that the net result isa deformation or flow of thelining material under circumstances which do not tend to cause fatigueor Wear or breakage.

While the form of the chamber 15 is ideal for the protection of thecombination liner and diaphragm, and the organization is also ideal inpositively precluding any leakage of the thermostatic material outwardlythrough the cylinder 25, I found unexpected difliculties in the use ofsome organizations of this kind if such organizations lack means forovercoming a tendency for recrystallization to occur along the wall ofthe liner while the central core of the composition remains soft. Inother words, after the relief of temperatures which have occasionedthermostatic response, the liner and plunger may not tend to return totheir original positions, even when subjected to considerable bias,until very substantial drops in temperature have occurred, this beingdue to the fact that the crystals used tend to form a bridge or domewithin the liner, which bridge has considerable strength to reducefurther inward movement of the liner and plunger.

The two separate means herein disclosed for meeting the problem haveproved entirely successful and both are desirably used, although eitherone alone is sufliciently successful to be practical. Reference is made,first, to the use of an inert filler or putty as above described, whichprevents the crystals from bridging and which facilitates their movementwith respect to another when they form, and, secondly, to the provisionof the heat conductive post at 31 or 310 which takes the heat out of thecenter of the body of composition 30 at a rate more rapid than the rateat which heat escapes from the upper portion of the body (which isrelatively insulated by the liner). Thus, when the fluid environment ofthe device becomes cooler, the first formation of crystals tends to bealong the inner surface of the uninsulated chamber section 17 and alongthe surfaces of the post 31 (or 310). Recrystallization of the activethermostatic material at these points results in contraction of suchmaterial as has crystallized and this happens while the rest of theactive material is still liquid and uncrystallized and, therefore,freely movable downwardly. Recrystallization proceeds from the bottom upand from the center outwardly and thus all portions of the liner remainin contact with liquid material or inert material untilrecrystallization is complete, the portion of the material nearest theliner being the last to crystallize because the liner has an appreciablethermally insulating effect.

A device of this character has an appreciably greater thermostaticresponse than devices of the same size which have previously been knownor used for this purpose and yet, despite its greater response, itsaction and reaction curves are as sharp or sharper, the speed ofretraction upon recrystallization being particularly great and beingcomplete Within a ten degree drop in temperature below the temperatureat which expansion occurs.

The device of Fig. 5 differs from that already described only in thefact that the interior of the liner is smoothly dome-shaped at 36, thecurvilinear throat portion of the chamber being completely filled withthe rubber plug 220, and the cavity extending upwardly throughout thethroat a r-easel at 37 of Figs. 2, 3 and 4 being completely eliminated.In this construction, there is more rubber tobe displaced in thedeformation which accomplishes the thermostatic action and theresilience of the rubber provides inherently a strong reactive pressuretending to restore the parts to the original form shown in Fig. 5. Inthis respect, the construction is similar to that shown in Fig. l of thecompanion application above identified;

Figs. 6 and 7 not only disclose the biasing spring as already described,but also disclose other features which are independently usable:

First, the chamber 152 is lined throughout its height and has anintegral bottom flange 38 rolled about a bottom closure 39 which mayalso be covered by a lining disk 40.

Secondly, the anchorage provided by the rolled flange 38 may, ifdesired, be supplemented or substituted by an adhesive connection of theliner to the casing in a limited zone at the remote end of the casing,as at 41.

Thirdly, the chamber liner may, as a separate feature, have its throatportion 242 materially thickened as compared with the throat portion 24of the liner in Figs. 2, 3 and 4.

Fig. 8 differs from the device of Fig. 7 only in that the chamber 153has an outwardly turned flange at 183 about which the liner flange 213'extends and is anchored by an upwardly rolled flange 193 on the bottomclosure 393, the bottom lining 40 being also omitted.

The device of Fig. 9 is identical with that of Fig. 8 except that aliner 404 has been added, the liner being extended outwardly to beclamped by the flange'194 of the bottom closure 394.

The device of Fig. 10 is identical as to its bottom closure with thedevice of Fig. 8, but it has a liner at 395 which is similar to thatshown at Fig. 6 except that it terminates short of the'clamping'engagement of the flange 393.

In the device of Fig. 11, the bottom closure 396 comprises a disk inclamping engagement with the outturned flange 216 of the liner, thebottom closure and the flange 183 of the receptacle being anchored underclamping pressure of the encircling channeled ring 205. The variousforms of closures of the means of clamping and forms of liners areinterchangeably usable where their respective advantages may be desiredand their respective disadvantages are immaterial. For general purposes,the construction of Figs. 1, 2 and 4 is a preferred construction.

Where reference has been made to rubber, it will be understood that theliner may be made of natural or synthetic rubber, the latter term beingintended to include a silicone.

In all forms of the device as hereinafter disclosed, the chamber andliner not only provides a diaphragm which makes a gasket unnecessary,but also provides a seal in the closing of the thermostatic chamber.Where the upper section of the chamber is'made of material which maybecorroded or otherwise aifected by the thermostatic composition used at30,the liner further protects the metal from such composition. Since thediaphragm portion of the liner is form-sustaining and provides a movablewall confining the composition 30, it will be obvious that any movablepart contacting the diaphragm portion of the liner will receive motiontherefrom, reference to the plunger being merely illustrative in this regard; It is unnecessary that the plunger be tightly fitted to thecylinder in the'sense that a piston is fitted to its cylinder.

I claim:

1. In a thermally responsive device of the character described, thecombination with a receptacle having communicating firstand secondchamber portions with means forsecurin'g said chamber portions inabutting relation with respect to each other, the first chamber portionhaving a cylinder witha. plunger guided for extensible "movementtherealong, said cylinder terminating, into a uniformly diverging throatextending into said first chamber portion and diverging into acurvilinear wall portion extending from said throat and forming a curvedwall uniformly converging into said cylinder, of an integral formsustaining diaphragm and skirt, the diaphragm extending across saidcylinder and being movable therealong and the skirt extending along saidthroat and wall and preformed to conform to the form thereof and forminga liner therefor, said skirt terminating into an outwardly turned flangeextending at substantially right angles to the body thereof and alongthe end face of said first chamber portion and clamped between the endfaces of said chamber portion by said means securing said chamberportions in abutting relation with respect to each other, said secondchamber portion being unlined and presenting a metallic heat conductingsurface, and a body of thermally expansive material filling said firstand second chamber portions within said liner.

2. The device of claim 1 in which said diaphragm is of materiallygreater thickness than the liner and comprises a plug substantiallyfilling portions of said throat adjacent said cylinder. 1

3. The device of claim 1 in which the second chamber portion comprises athermally conductive core about which said body of material is disposed.

4. In a thermally responsive device of the character described, thecombination with a receptacle having first and second chamber portionscommunicating with each other with means for securing said chamberportions in abutting communicating relation with respect to each other,the first chamber portion having a cylinder having a plunger guided forextensible movement therealong and terminating within said chamber intoa uniformly curved diverging throat and having a curvilinear wallportion extending from said throat, of an integral form sustainingdiaphragm and skirt, the diaphragm extending across said cylinder andbeing movable therealong and the skirt extending inwardly from saiddiaphragm along said throat and the wall of said first chamber portion,and being formed to conform to the form of said throat and wall andforming a liner for said first chamber portion, said skirt having anoutwardly turned flange extending at substantially right angles to thebody thereof, beneath and along the end of said first chamber portionand clamped to the end of said second chamber portion by means forsecuring said chamber portions together, said second chamber portioncomprising a cup shaped chamber providing an unlined metallic surface ofconcave form and of substantial extent, and a body of thermallyexpansible material in direct thermal contact with said wall of saidsecond chamber portion and filling said first chamber portion withinsaid liner.

5. in a thermally responsive device of the character described, a hollowtwo-part receptacle, each part of which has a chamber portion, onechamber portion terminating into a cylinder having a plunger extensiblymovable therealong and having a throat diverging from said cylinder anduniformly curving into a generally cylindrical wall, the other chamberportion being of a generally cup-like form and abutting and closing theend of the cylindrical wall of said one chamber portion, a diaphragm insaid cylinder engaging said plunger and having a preformed skirt formedto the curvature of said throat and wall extending from said diaphragmalong said throat and cylindrical wall and forming an insulating mediumfor said one chamber portion, a body of thermally expansible materialfilling said chamber portions, and the other chamber portion having athermally conductive post extending upwardly into the body of thermallyconductive material and with the wall of said other chamber portionforming an annular thermally conductive channel for the thermallyexpansible material, conducting heat from the thermally expansiblematerial upon cooling and precluding bridging of the crystals of thethermally expan ible material as the material changes in state fromliqui to solid.

6. In a thermally responsive device of the character described, a hollowtwo-part receptacle, each part of which has a chamber portion, onechamber portion terminating in a cylinder having a plunger extensiblymov able therealong, and having a throat forming an inner continuationof said cylinder and uniformly curving from said cylinder into agenerally cylindrical wall, the other chamber portion being of agenerally cup-like form, a diaphragm extending across said cylinder andengaging said plunger and having an integral preformed skirt extendingtherefrom, conforming to said throat and the wall thereof, and formingan insulating medium for said one chamber portion and having a flangeextending along the end of the cylindrical wall of said one chamberportion in abutment with the end of the other chamber portion andsecured thereto by the means for securing said chamber portionstogether, a body of thermally expansible material filling said chamberportions comprising crystals expansible on melting and contractable oncrystallization, the inner wall of said other chamber portion beingmetallic, and means precluding the bridging of the crystals of thethermally expansible material upon changes in state thereof from aliquid to a solid, comprising a hollow post extending upwardly into theother chamber portion and with the inner wall of said other chamberportion forming a metallic annular channel adapted to conduct heat fromthe thermally expansible material.

7. The device of claim 6 in which said post is solid.

8. A thermostat comprising a casing with fixed wall portions defining acavity of relatively large cross-section and converging at one end to areduced diameter cylinder extending therefrom having a diaphragmextending across said cylinder and forming a movable wall portion ofsaid chamber and lining a portion of the wall of said cavity and formingan insulating means therefor and movable along said cylinder uponpredetermined increases in temperature, the other portion of the wall ofsaid cavity being metallic, a body of thermostatically expansiblematerial in said casing confined by said wall portions for effectingmovement of said diaphragm along said cylinder upon expansion of saidbody, said thermally expansible material comprising a normallycrystalline substance distributed in a putty of finely divided powderand an oil which expands as it melts, and means for precluding thebridging of the crystals of said substance across said diaphragm uponcooling and recrystallization thereof comprising a metallic thermallyconductive core extending Within said cavity and terminating in a regionremote from said diaphragm and conducting heat from said cavity andforming with said cavity an annular metallic channel about whichcrystals tend to form.

9. The combination with a two-part receptacle, the respective partshaving flanged margins and clamping means securing said margins, one ofsaid parts having a cylinder portion of materially reduced cross sectionas compared with the receptacle, a flexible partition spanningthereceptacle between said parts and having its margins onfined betweenthe flanges of said parts, a flexible ahd resiliently elastic linerhaving a flange confined between the flanges of said parts and having awall portion conforming interiorly to the wall of the receptacle partprovided with the cylinder, said liner terminating in a wall disposedtransversely of the cylinder, a body of at least plastic semi-fluidmaterial confined within said liner and partition and wall portion tosubstantially fill the space between the wall portion and the liner inthe part of said receptacle provided with said cylinder, and a thermallyexpansible material comprising crystals confined in and substantiallyfilling the other part of said body and separated from the firstmentioned material by said partition.

10. The device of claim 9 in which the said other part of the receptaclehas a metallic wall and a core portion connected with said wall andcomprising a-metal of a high thermal conductivity and extending into thecrystal material.

11. The device of claim 10 in which said partition normally seats uponthe core portion in the contracted state of the crystalline material.

12. In a thermally responsive device of the character described, thecombination with a receptacle having first and second chamber portionscommunicating with each other with means for securing said chamberportions in abutting communicating relation with respect to each other,the first chamber portion having a cylinder having a plunger guided forextensible movement therealong and terminating within said chamber intoa uniformly curved diverging throat and having a curvilinear wallportion extending from said throat, of an integral form sustainingdiaphragm and skirt, the diaphragm extending across said cylinder andbeing movable therealong and the skirt extending inwardly from saiddiaphragm along said throat and the Wall of said first chamber portion,and being formed to conform to the form of said throat and wall andforming a liner for said first chamber portion, said skirt having anoutwardly turned flange extending at substantially right angles to thebody thereof, beneath and along the end of said first chamber portionand clamped to the end of said second chamber portion by the means forsecuring said chamber portions together, said second chamber portioncomprising a cup-shaped element having an unlined annular chambertherein for a body of thermally expansible material, and the thermallyexpansible material filling said unlined chamber portion and fillingsaid second chamber portion within said liner.

13. In a thermally responsive device of the character described, ahollow two-part receptacle, each part of which has a chamber portion,one chamber portion terminating in a cylinder having a plungerextensibly movable therealong, and having a throat forming an innercontinuation of said cylinder and uniformly curving from said cylinderinto a generally cylindrical wall, the other chamber portion being of agenerally cup-like form, a diaphragm extending across said cylinder andengaging said plunger and having an integral preformed skirt extendingtherefrom, conforming to said throat and the wall thereof, and formingan insulating medium for said one chamber portion and having a flangeextending along the end of the cylindrical wall of said one chamberportion in abutment with the end of the other chamber portion andsecured thereto by the means for securing said chamber portionstogether, a body of thermally expansible material filling said chamberportions comprising crystals expansible on melting, and contractible oncrystallization, the inner wall of said other chamber portion beingmetallic, and means precluding the bridging of the crystals of thethermally expansible material upon changes in state thereof from aliquid to a solid comprising a metallic annular channel in the other ofsaid chambers, the inner wall of which conducts heat from the thermallyexpansible material.

References Cited in the file of this patent UNITED STATES PATENTS FranceIan. 27, 1931

